1. Field of the Invention
The present invention is directed to a liquid crystal display (LCD) panel and an active matrix substrate thereof, and more particularly to an LCD panel with wide viewing angle and an active matrix substrate thereof.
2. Description of Related Art
Nowadays, the functions that the market demands of the thin film transistor liquid crystal display (TFT-LCD) tend to be high contrast ratio, high luminance, quick response and wide viewing angle. Currently, the technologies that meet the requirement of wide viewing angle include, for example, the twisted nematic (TN) LCD with a wide viewing film, the in-plane switching (IPS) LCD, the fringe field switching (FFS) LCD and a multi-domain vertical alignment (MVA) TFT-LCD. In the conventional MVA-LCD panel, since alignment protrusions or slits formed on the color filter substrate or the TFT array substrate can render the liquid crystal molecules arranged in multiple directions, thereby achieving multi-domain. Therefore, the MVA-LCD panel can meet the requirement of wide viewing angle. However, the technique of achieving multi-domain by the said slits often results in greater instability of the multi-domain because the tilted electric field generated by the slits is weaker in its intensity.
Moreover, although the conventional MVA-LCD panel meets the requirement of wide viewing angle, it has the problem of color shift. The so-called color shift means users would see an image having gray scales different from the original image when viewing the images on the display device from different viewing angles. For example, users would see an image lighter than the original image if viewing from a large angle. The problem of color shift would deteriorate the display quality of the image. In order to solve the problem of color shift, some solutions have been proposed, and one of the solutions is forming an additional capacitor in one single pixel unit. By electrical coupling, the capacitor makes a pixel electrode within the single pixel unit generate electric fields of different intensities, and thereby generating different arrangements of liquid crystal molecules. Although the method can mitigate the phenomenon of color shift, it tends to result in the resistance-capacitance (RC) delay effect and thus causing distorted image and poor display quality.
Another method is adding one more transistor in one single pixel unit. In other words, one single pixel unit has two transistors. The two transistors make the pixel electrode in the single pixel unit generate different electric fields and thus generating different arrangements of liquid crystal molecules and thereby eliminating color shift. Nevertheless, the method requires two transistors to be formed in one single pixel unit and more conductive lines to be added (such as scan lines) so that the fabricating process is made complicated and the fabricating cost higher as well.